Easy Ways to Remember the Progression of MRI Signal Intensity Changes of Intracranial Hemorrhage

Canadian Association of Radiologists Journal 60 (2009) 88e90
www.carjonline.org
Neuroradiology / Neuroradiologie
Easy Ways to Remember the Progression of MRI Signal Intensity
Changes of Intracranial Hemorrhage
Zeev V. Maizlin, MDa,*, Jason R. Shewchuk, MDb, Jason J. Clement, MDc
a
Department of Radiology, McMaster University Medical Centre, Hamilton, Ontario, Canada
b
Medical Imaging, Royal Columbian Hospital, New Westminster, British Columbia, Canada
c
Radiology, St Paul’s Hospital, Vancouver, British Columbia, Canada
The magnetic resonance imaging (MRI) appearance of
intracranial hemorrhage was reviewed by Bradley [1]. It
depends primarily on the age of the hematoma and the type
of MR contrast (T1 or T2 weighted). As a hematoma ages,
the hemoglobin passes through several forms: oxyhemoglobin in the hyperacute phase, deoxyhemoglobin in the
acute phase, intracellular methemoglobin in the early
subacute phase, extracellular methemoglobin in the late
subacute phase, and hemosiderin in the chronic phase. The
evolution of MRI appearances of a parenchymal hematoma
is shown in Table 1 with an approximate time scale.
Several techniques have been proposed to remember the
progression of MRI signal intensity changes occurring in
hematomas with time. These mnemonics are summarized in
Figure 1.
One of the authors (J.R.S.) uses a graphic chart
(Figure 2) to follow the sequence of signal changes in
parenchymal hematomas. T1-weighted (T1W) signal intensity (SI) is represented on the horizontal axis and T2weighted (T2W) SI is represented on the vertical axis. The
graph contains 5 points, corresponding to the 5 phases of
hemoglobin evolution. It is drawn counterclockwise, as an
incomplete square, through points 1 to 4, then diagonally to
point 5. The arrow on the fifth point helps to remember the
direction of the process. To help remember how to label the
axes one can imagine hyperacute blood to essentially be
free fluid immediately after becoming extravascular. Fluid
has high T2W SI, and thus the vertical axis represents T2W
SI.
Kaplan et al [2] described a sophisticated mnemonic
imported by one of their fellows from Canada, ItBe IdDy
BiDdy BaBy DooDoo. In this phrase each word represents
a phase of evolving blood products (in chronologic order),
the bold letters in each word represent the T1W SI and T2W
SI, respectively, and I ¼ intermediate, B ¼ bright, and D ¼
dark (low) signal intensity.
The use of combinations of fingers also was proposed to
remember the appearance of a hematoma on MRI. The digits
are labeled O, D, I, E, and H (oxyhemoglobin, deoxyhemoglobin, intracellular methemoglobin, extracellular
methemoglobin, and hemosiderin) from pinky to thumb. One
hand represents T1W SI and the other represents T2W SI. On
the T1W SI hand the index and middle fingers are extended,
and on the T2W SI hand the pinky and index fingers are
extended. All other digits are flexed (Figure 3). Flexed digits
represent low or intermediate SI, and extended digits represent high SI.
In our opinion, the graph method is easiest to remember.
This may be because radiology is a highly visual specialty,
and visual mnemonics seem easier to remember. We find the
hand method the most difficult, requiring one to remember
how to position the fingers in each hand. However, learning
preferences are highly individual.
Original sources for the graph and finger combination are
unknown. There are likely other memory devices also in use.
We present these techniques to help those learning the MRI
evolution of intracranial hemorrhage.
References
[1] Bradley WG Jr. MR appearance of hemorrhage in the brain. Radiology
1993;189:15e26.
[2] Kaplan PA, Dussault R, Helms CA, et al. Musculoskeletal MRI. Philadelphia (PA): Saunders; 2001:71.
* Address for correspondence: Zeev V. Maizlin, MD, Department of
Radiology, McMaster University Medical Centre, 1200 Main Street West,
Hamilton, Ontario L8N 3Z5, Canada.
E-mail address: [email protected] (Z. V. Maizlin).
0846-5371/$ - see front matter Ó 2009 Canadian Association of Radiologists. All rights reserved.
doi:10.1016/j.carj.2009.02.011
Z. V. Maizlin et al. / Canadian Association of Radiologists Journal 60 (2009) 88e90
89
Table 1
Evolution of intracranial hemorrhage appearance on MRI
Stage
Hyperacute
Acute
Early subacute
Late subacute
Chronic
Age
<24h
1e3 d
>3 d
>7 d
>14 d
Stage
Hemoglobin
Oxyhemoglobin
Deoxyhemoglobin
Intracellular methemoglobin
Extracellular methemoglobin
Hemosiderin
Point
on the graph
(Figure 2)
T1W SI
Isointense
Isointense to hypointense
Hyperintense
Hyperintense
Hypointense
Mnemonic
Hyperacute
1
ItBe
Acute
2
IdDy
Early Subacute
3
BiDdy
Late Subacute
4
BaBy
Chronic
5
DooDoo
T2W SI
Hyperintense
Hypointense
Hypointense
Hyperintense
Hypointense
Finger combination
(Figure 3)
Figure 1. Mnemonic techniques for the progression of MRI signal intensity changes in hematomas.
Point on the graph
(Figure 2)
1
2
3
4
5
90
Z. V. Maizlin et al. / Canadian Association of Radiologists Journal 60 (2009) 88e90
Figure 2. Mnemonic graph describing the progression of MRI signal intensity changes of intracranial hemorrhage.
Figure 3. Mnemonic hand memory device describing the progression of MRI signal intensity changes of intracranial hemorrhage. O¼oxyhemoglobin;
D ¼ deoxyhemoglobin; I ¼ intracellular methemoglobin; E ¼ extracellular methemoglobin; H ¼ hemosiderin.